Joining the long list of factors that may or may not make your babies come out smarter or dumber or nicer or meaner or gayer or taller or fatter or fartier: Now it looks like babies that stay in the womb longer might have a greater chance of behavioral and emotional problems such as ADHD. So pop 'em out, ladies! Pop those suckers out ASAP.*

A Dutch study, which examined 5145 children and their parents, has found that post-term babies had "about twice as likely to have parent-reported symptoms consistent with ADHD." The study didn't establish any kind of direct causal relationship, but researchers found a significantly higher likelihood of neurodevelopmental delays in children born at 42 weeks or higher.

The study offers several potential explanations for the correlation:

First, post-term babies are more likely to be bigger than those born at term and thus have a greater risk of a lack of oxygen around the time of delivery. That lack of oxygen has been associated with behavioral problems.

In addition, insufficient nutrients and oxygen in a post-term placenta could increase the risk of abnormal fetal development, according to the researchers. It also is possible that a hormonal disturbance involved in managing the length of pregnancy could be a factor.

The researchers also note that relying on self-reporting parents—whose awareness of their child's post-term birth might skew their answers—could introduce some inaccuracies into the data. And even if they do eventually find a direct causal link between long pregnancies and behavioral problems, it certainly doesn't mean that kids who stay in the womb too long are destined to become evil, hyperactive bullies (in fact, if television teaches us anything, it's that the opposite is true). But this study could prove extremely helpful in the long run— for people looking to minimize the long-term negative effects of ADHD, I can't think of a more efficient starting point than birth.